Session: 01-09 Modelling, Simulation and Validation I

Paper Number: 154080

Ceramic Composite Materials Investigated for Suitability in Dynamic Sealing Conditions 

Dynamic face seals are used in rotating aerospace (engine gearbox and drive shaft) and industrial applications to maintain pressure differentials, prevent fluid leakage, and protect equipment from the external environment. Current dynamic face seal applications use a carbon stator due to carbon’s self-centering and self-lubricating properties. Carbon stators cover a wide range of applications but have limited use in both low speed-high load and high speed applications. During low speed-high load conditions, the lubricious graphite film is stripped to expose structural amorphous carbons.  Without solid-state lubrication from graphene, hard amorphous carbon structures act as abrasives that cause increased friction, and static buildup. At high speeds, energy lost to friction results in elevated temperatures, oxidizing exposed carbon surfaces and causing oil coking in systems with lubricating oils. Oxidized carbon does not retain self-lubricating properties and instead becomes abrasive to contacting surfaces, causing detrimental wear on carbon at the contacting interface. Current alternate materials used in these applications include carbides such as self-sintered Silicon-Carbide (SiC) and Tungsten-Carbide (WC) with cobalt or nickel additions. 

This work investigates alternative ceramic materials for improved performance in these particular environments. Al2O3-alternate oxide ceramic composites show promising low friction properties. This study investigates the effect of initial powder size and ratio of Al2O3 and alternate metal oxide powders on the final mixed microstructure, dynamic coefficient of friction, roughness, and wear depth. The novel ceramic material has higher compressive strength than carbon which, in a homogenous structure, may prevent the particulate breakdown that causes excessive wear in carbon at low speed-high load applications. Additionally, the ceramic system will not experience phase changes (unlike the oxidation of graphite) so mechanical properties are constant at the high temperatures induced by high rotational speeds.  

Linear reciprocation testing was performed with tungsten carbide pins at 10N and 150N loads on initial ceramic samples of various starting powder sizes and ratios. Friction testing, profilometry, X-ray diffraction (XRD), and scanning electron microscopy (SEM) were used to analyze the effect of wear, surface roughness, density, and phase composition; all tests were replicated on carbon and carbide materials for comparison. Low alumina powder ratios with smaller alumina starting powder size demonstrated the lowest dynamic coefficients of friction, most similar to the performance to carbons. A dynamic testing rig will be used in future testing on the best performing ceramic systems in similar service conditions experienced by dynamic face seals.  

Presenting Author: Erin Volpe Technetics Group

Presenting Author Biography: Erin works as an R&D test engineer for Technetics Group. In her current role she investigates mechanical and thermal properties of materials in sealing applications. Erin received a Bachelor's Degree in Engineering from the University of Florida.

Authors:

Erin Volpe Technetics Group
Shannon Depratter Technetics Group
Carolyn Grimley Lucideon
Becca Jones Technetics Group
Elaine Motyka Technetics Group
Ryan Plessinger Technetics Group
Stefan Roeseler Technetics Group
Tyler Noyes Technetics Group
Jonathan Kweder Technetics Group